<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <ul>
        <li>111111</li>
        <li>22222</li>
        <li>33333</li>
        <li>44444</li>
        <li>555555</li>
    </ul>
    <div id="box">
        <div>111111</div>
        <p>这是一个p</p>
        <span>这是一个span</span>
        <p class="cont">ppppppppp</p>
        <p>111111</p>
        <p>111111</p>
    </div>
        <p>hellohello</p>
        <p class="selsected">Hello Again1</p>
        <p class="selsected">Hello Again2</p>
        <p class="selsected">Hello Again3</p>
        <p class="selsected">Hello Again4</p>
        <p class="selsected">Hello Again5</p>
    <div>
        <span>这是span2</span>
        <p class="selsected">Hello Again6</p>
    </div>
    <script src="./jquery-1.12.4.js"></script>
    <script>
        // 语法:children() 获取元素的所有的子元素
        $(function(){
            // alert($("#box").children().length)
            // 对一组元素进行统一操作
            // 分别对每一个元素操作要用到循环
            // $("#box").children().css("background","red")

            // 做过滤操作
            $("#box").children(".cont").css("background","red")
        })
    </script>
</body>
</html>